Propeller mechanism



Jan. 5, 1943.

W. J. BLANCHARD ETAL PROPELLER MECHANISM Filed June 16, 1939 3Sheets-Sheet 1 1943- w. J. BLANCHARD a-rm. 2,307,101

PROPELLER MECHANI SM Filed June 16, 1939 3 Sheets-Sheet I5 Patented Jan.5, 1943 PROPELLER MECHANISM Werner J. Blanchard and Charles S. J.MacNeil,

Dayton, Ohio, assignors to The Winters National Bank and Trust Company,Dayton, Ohio, a national banking corporation, as trustee ApplicationJune 16, 1939, Serial No. 279,530

18 Claims. (Cl. 170-163) This invention relates to propellers and moreparticularly to propellers having hydraulically adjustable blades.

It is a principal object of the invention to provide a propeller havinghydraulically adjustable blades which is simple in construction and inwhich the blades are adjustable both rapidly and accurately over a widerange of positionings, such as from a negative pitch position to afeathered position.

It is a further object to provide a propeller of this character in whichthe blades are held in a predetermined operating position through thenormal range of flight positions against the action of the centrifugalforces to which the propeller I is subjected, and are actuated in bothpitch-increasing and pitch-decreasing directions by selectively appliedhydraulic pressure.

It is a still further object to provide a propeller of this character inwhich the mass of the operating parts and forces encountered in use aredistributed around the periphery of the blade to avoid excessivelocalized loads and unbalanced centrifugal forces.

It is a further object to provide an adjustable propeller blade which isrelatively slowly and accurately adjustable as to its angularpositioning over the normal working range of the blade and which is morerapidly movable from the working range into a feathered position toprovide for securing rapid and accurate overall adjustment.

It is also an object to provide such a propeller in which the actuatingmechanism is located within the propeller hub out of alignment with thedriveshaft, leaving the driveshaft clear for the purpose of firingprojectiles or the like therethrough.

Other objects and advantages will be apparent from the followingdescription, the accompanying drawings, and the appended claims.

Inthe drawings- Fig. 1 is an end elevational view of a propeller hubconstructed in accordance with the present invention, certain of theparts being broken away to more clearly show the construction;

Fig. 2 is a vertical sectional view through the axis of one of theblades on the line 2-2 of Fig. 1;

Fig. 3 is a broken end elevational view of the hub with parts brokenaway and showing the opposite end from that shown in Fig. 1;

Fig. 4 is a horizontal section through the blade socket on the line 4-1of Fig. 3 showing the connection; and

Fig. 5 is a diagrammatic view illustrating the combined rapid and slowspeed adjustment for the angular positioning of the blades.

Referring to the drawings which show a preferred embodiment of theinvention, a hollow driveshaft is shown at l0 and is provided with theusual spline II for receiving and driving the main hub l2, which has acooperating spline connection. The hub is formed integrally with theblade sockets |3 in the number desired, illustrated in the drawings ascomprising three such sockets. The hub is retained in proper positionupon the shaft by means of a wedge ring I and a locking nut l5threadedly received upon the end of the shaft.

The blades are shown at 20, and as illustrated in Fig. 2 comprise ahollow root portion 2|. The inner ends of the blades are received withinthe sockets l3, and retained therein in rotatably adjustable positionagainst the outward centrifugal force. The means for so retaining theblades comprises a clamping ring 22 threadedly received upon the shankof the balde and having bearing engagement upon a series of ballbearings 23 surrounding the blade, and in turn retained in positionwithin the blade sockets by means of a retaining nut 24 threaded intothe socket. Provision is made for adjusting and for fastening the nut inpredetermined position in the .usual way through the use of a lockingmember 25 fastened to the retaining nut and cooperating with one of aseries of notches formed in the outer periphery of the blade socket.This construction provides for retaining the blade in the socket whileproviding for the angular movement and adjustment thereof with respectto the socket.

In order to effect rotation of the blades in their sockets to adjust thepitch angle thereof, each blade in the hollow root portion 2| thereof isprovided with hydraulic actuating mechanism. This mechanism as showncomprises a stationary cylindrical member which is pinned fast to thehub l2 centrally of the blade by means of dowel pins 3|, and extendsradially outwardly thereof into hollow portion 2|. At its outer end thissleeve carries a pair of clamping rings 32 and 33 which are bolted at 34to the end of the sleeve, and which are provided with packing material35 therebetween. The clamping rings 32 and 33 are provided with coaxialpassages for receiving a tubular pistonrod 36 which extendstherethrough, the construction thus described providing for the movementof the piston rod through the clamping means in fluid sealed relationwith respect thereto.

Member 39 is provided on its outer periphery with spirally arrangedspline teeth 49 having a relatively small angle of lead. Operativelyengaged therewith is a piston skirt or sleeve member 4| havingcooperating spline teeth 42 upon its inner periphery, having the samehelix angle as teeth 49 to provide for intermeshing engagementtherebetween. The skirt member 4| is formed integrally with and as anextension of the weighted piston head 43. The piston rod 36 is bolted tothe piston head by means of bolts 44 passing through an outwardlyprojecting flange 45 formed integrally with the piston rod. Suitableflexible members or cups 46 are likewise carried by the piston forsealing engagement with the wall of the cylinder 41.

The cylinder 41 also received within the hollow blade root is closed atits outer end by means of wall 48, and at its inner end is provided withan outwardly turned flange 49 which engages over the end of the bladeroot 29, being pinned thereto by means of pins 59 so that the cylinder48 is caused to rotate along with the blade. Suitable fluid sealingmeans is provided to prevent loss of fluid pressure from the interior ofthe cylinder.

In order to efiect rotation of the cylinder 41 in response to movementof piston 43 radially of the propeller axis, and to secure both rapidand accurate positioning of the blade, use is made of an interconnectingmeans effective between the piston and the cylinder to give the desireddegree and accuracy of control. As already described, the skirt 4| ofthe piston is provided with helical spline teeth 42 upon its innerperiphery for engagement with helical spline teeth 49 formed upon thestationary member 39. .The outer periphery of the skirt 4| is 1ikewiseprovided with helical spline teeth 55 which operatively engage withhelical spline teeth 59 formed upon the inner periphery of a floatingspline member 51. The helix angle of teeth 55 and 56 is the same, but ispreferably of a greater angle of lead than that of teeth 49 and 42, thepurpose of which will be described hereafter. Floating spline member 51likewise has helical spline teeth 59 formed upon its outer peripherywhich engage with helical spline teeth 59 formed upon theinner peripheryof the cylinder 41. Teeth 59 and 59 have the same angle of lead, whichis preferably smaller than that of teeth 55, 56, and comparable withthat of teeth 49, 42. As an example of said construction, the angle oflead of teeth 49, 42, 58, and 59, is made 20, while that of teeth 55, 59may be 45.

Skirt 4| is provided with a series of passages 52 through the wallthereof outwardly of the several spline constructions as described, andis likewise formed with an outwardly projecting finger 93 which isadapted to engage the end of floating spline member 51 in order to causepositive movement thereof. Cylinder 41 is likewise provided with aninwardly projecting extension 54 which is adapted to have engagementwith the outwardly projecting nose 65 of the floating spline member 51in order to limit the outward movement thereof.

To guide the blade in its rotational movements the base of member 89 isprovided with a roller bearing 55, the outer race being carried in theflange'5l of a bevel gear 59, which is pinned to the the blade root bypins 59.

Means are provided for supplying actuatin fluid under pressure toeffectadjustment in the setting of the blades. In the particular arrangementshown provision is made for selectively applying fluid in order toeffect both increase and decrease in the pitch angle setting of theblades. Control of the supply of such pressure actuating fluid isprovided through the use of a regulator device where it is desired tohave a constant speed of rotation of the propeller. A preferredregulator for this purpose is that disclosed in copending applicationSerial No. 279,531, filed concurrently herewith, in which the regulatorcomprises a self-contained unit and is rotatable with the propeller hub,thereby avoiding the necessity for transmitting fluid from a stationaryto a rotating part, with elimination of the necessity for packed glandsand the like. In addition to this preferred form of regulator, othercontrol means for selectively supplying the actuating fluid may beutilized as desired.

As illustrated in Fig. 2, the regulator 19 is carried by the driveshaftI9 so as to be rotatable therewith and standing directly adjacent therear face of the hub l2 and the several blade sockets l3. With suchregulator there are provided concentric passages II and 12 at differentradial spacings, preferably extending around the entire periphery.Pressure fluid is pumped from a reservoir formed by the outer casinginto an outer passage 13 from which it i automatically and selectivelysupplied to one or the other of passages 1| and 12 in accordance withthe functioning of the regulator mechanism, and as determined by theconditions of propeller speed, pressure being supplied into one of saidconduits (1|) upon a drop in speed. and to the other (12) upon anincrease in speed.

Means are provided in the hub for introducing fluid from each of thepassages selectively into the root portion of each of the propellerblades, to effect change in the pitch angle setting of the blades in amanner corresponding to the supply of pressure fluid thereto, and tomaintain a desired speed condition of the blade. This means comprises anut 15 which is threaded into the hub through the base of cylindricalmember 39 and provided with an axial bore 19 establishing communicationbetween the interior of cylindrical member 39 and a central recess 11formed in the hub |2. A tube 19 leads from recess 11 to the rear face ofthe socket I! where it communicates with a connectin tube 19 projectingfrom the face of the socket and having such radial positioning from thepropeller axis as to be in line with the passage 1| of the regulatordevice. Connection 19 extends through the wall 89 of the regulatordevice and thus establishes direct communication for the passage offluid from the passage 1| into the interior of member 99. It will beobserved by reference to Fig. 3 that each of the several blade socketsis provided with a similar such connecting device 19, all of saiddevices being located on the same radius so that each one of them hasdirect and individual communication with passage 1|.

Upon application of fluid pressure to passage II, it is directlysupplied into each of the cylindrical member 99 in each of the severalblade sockets, and from there it flows through the respective pistonrods 35 into the space 9| formed outwardly of the piston member 43. Thusin response to such pressure application each piston is caused to moveradially inwardly.

In order to effect the application of pressure on the opposite side ofthe piston to cause outward movement thereof, a passage (shown in Fig.4) is formed in the inner wall of member 30 leading into the annularspace 85 between member 84 and cylinder 47. This passage extendsdownwardly, in substantially the location of one of the dowel pins 3|which it replaces, to a plane substantially the same as that containingtube 18. A similar tube 88 leads from the passage 85, through the hub,and to the outer rear face of the socket, emerging therefrom with aconnecting tube 89 at a different and greater radial distance from thepropeller axis than tube 19. Each of the tubes 89 is thus brought out tocommunicate through the wall 80 of the regulator with the passage I2 sothat fluid is supplied therethrough into each of the propeller rootportions, and into the chambers 86 as described above.

The several spli'ne teeth which occupy space 86 are formed withsuflicient clearance between adjacent teeth to providev for passage ofthe fluid through and over the splined surfaces, thereby providing asource of lubrication under pressure for such working surfaces. Thefluid is then transmitted above the splined teeth into the annular space99, from which it passes through apertures 82 into the space 9| formedbeneath the piston and above the fixed end of member 30. Consequentlywhen pressure is applied through passage 12, that pressure iscommunicated to and is simultaneously made effective upon the inside ofeach piston 43 to effect outward movement thereof, it being understoodthat when fluid pressure is applied upon one side of the piston 43 thepressure is released upon the other to permit of back flow of fluidtherefrom.

In the operation of the device constructed in accordance with thisinvention, and assuming it is desired to increase the pitch angle of theblades, either from a small positive or from a negative angle position,fluid pressure is applied through the passage 12 and made effective uponthe inner face of piston 43 in the manner just described. As a result ofthis pressure, piston 43 moves outwardly with respect to the member 30and cylinder 41. As the sleeve 4| is thus moved outwardly, spline teeth40 and 42 cause a twisting or rotation to occur in the piston and pistonextension relative to the fixed member 30. However this outward movementof sleeve 4| also tends to effect relative movement between spline teeth55, 56 and between teeth 58, 59. Because the pitch angle of spline teeth58, 59 is less than that of teeth 55, 55, there is less resistance tothe relative sliding as between teeth 58 and 59 than as between teeth 55and 56. Therefore the initial movement all takes place between teeth 58,59, teeth 55, 56 remaining locked together. The cylinder 41 is thuscaused to rotate with a movement which is the sum of that caused byspline teeth 49, 42 and 58, 59, in the direction from left to right asshown in Fig. 2. This movement is relatively slow, so that a ratherextended travel of the piston during this initial portion of the bladerotation results in adjustment of the blade within substantially thenormal working range of the blade. Thus for example with the arrangementshown a movement of the piston 43 of two inches at the beginning of itsoutward travel is made to effect an angular adjustment of the bladeposition of approximately 50. This is generally sufficient to cover thenormal working range of positions of the blade, even beginning with anegative blade position of as much as -12, and can be increased ifdesired. Since the extent of travel of piston 43 is subject to accuratecontrol, the pitch angle of the blade is also determined with a. highdegree of accuracy and the speed is maintained within narrow limits suchthatyobjectionable noise and vibrations are overco e.

i li lhen the normal range of operative positions of. the blade in whichconsiderable accuracy of setting and fineness of adjustment are desired,has been covered, provision is made for rapidly moving the blade intoits fully feathered position, with a relatively reduced amount ofadditional piston travel. In accordance with the present constructionthis is provided by the use of the floating spline construction as abovedescribed. As the piston 43 continues to move outwardly carrying thefloating spline along with it, the nose 65 of the floating splineadvances outwardly to a position where it contacts with the overhangingprojection 54 of the cylinder. Thereafter the floating splineisprevented from further outward movement. Upon continued application ofhydraulic pressure upon the inner face J left or right.

of the piston, the piston is caused to move outwardly against the nowstationary spline member 51. As a result of this action, and because ofthe greater angle of lead of spline .teeth 55, 55, additional outwardmovements of piston 43 result in proportionately greater turning of thecylinder 41 and with it of the blade. It will be noted that under theseconditions the rotary movement of cylinder 41 becomes the sum of thatproduced by spline teeth 40, 42 and 55, 58 and the blade is thus movedrapidly into higher pitch positions and if desired finally into a fullyfeathered position.

In order to effect the restoring of the blade to a lower pitch position,substantially the reverse operation takes place. That is to say, withthe blade in a fully feathered position, pressure is supplied throughpassage tube 18, passage 15 and through tubularpiston rod 36 intothepassage 8| above piston 43. Piston 43 is thus caused to move radiallyinwardly effecting rotation thereof in the reverse direction by reasonof spline teeth 48,42. Alsobecause of the greater angle of lead ofspline teeth 55, 55, initial piston movement results in relativemovement occurring therebetween, teeth 58, 59 meanwhile remaininglocked. Hence the blade is quickly returned from its fully feath- I thesleeve 4| to contact the floating spline and to thereafter eflectrelative rotation as between spline teeth 51 and 58 as well as betweenteeth 40 and 42.

The operations as described above are illustrated diagrammatically inFig. 5 where the piston 43 is shown as traveling in the direction of thearrow, and in such manner as to produce a resultant rotational movementof the blade, illustrated as a lateral movement of member 41' to Thismovement corresponds to the sum of the leads of surfaces 40', 42' and58', 59'. Because surfaces 55 and 59' have a greater angle, no relativemovement takes place initially therebetween. However as the movement ofthe piston continues, floating member 51' strikes nose 84' of cylinder41' and further movement is terminated; thereafter relative movementbetween surfaces 55' and 58' takes place, resulting in a correspondinglygreater lateral displacement,

Upon reverse movement of the piston, initial movement occurs betweensurfaces 55' and it until nose 63' returns into engagement with member51, thereby causing relative movement between surfaces 58' and 59.

Each of the several blades is preferably provided with actuatingmechanism of this character, and the constants are preferably chosen soas to substantially balance the forces of blade torque at a suitablepoint in the operative range. Thus the centrifugal blade torque actsupon the blade to tend to reduce it to a lower pitch position. Opposedto this force is the centrifugal force which is effective upon thepiston, the piston skirt, and associated parts. While the weight ofthese parts may be varied to secure a balancing of the oppositely actingforces at different blade positions, a satisfactory arrangement is toprovide such weight in the piston 43 that it will be in substantiallybalanced relation with the centrifugal blade torque at a blade angle ofabout 40. With the splined construction as shown the forces acting tocause rotation of the blade are uniformly distributed around the entireperiphery of the operating parts and hence a well balanced condition ismaintained, avoiding excessive loads in localized areas and stressesresulting from unbalanced centrifugal forces. With the forces resultingfrom the weight of the piston, centrifugal blade torque, etc.,substantially balanced in the operative range, the blade will have astatic position so that it will retain such setting in the absence ofany application of fluid actuating pressure. And by reason of thefrictional forces opposing a shifting of the spline members relative toeach other in either direction, the actual range over which the bladehas a static condition is relatively wide, and in practice may readilybe such as to cover substantially the normal operating range of bladeangle positions. As a result therefore a highly satisfactoryconstruction is provided in which, with the blade in a normal operatingposition, it is necessary only to effect the application of fluidpressure to one side of the piston or the other to secure a change inthe setting of the blade, and thereafter it is no longer necessary tomaintain pressure upon the piston, the blade being frictionally retainedin the desired adjusting position.

By suitably changing the constants of the weight of the piston inrelation to the factors which produce centrifugal blade torque, theblade can be overbalanced or underbalanced as desired, to such extent asto utilize such forces for the shifting of the blade in one direction,and making use of the fluid pressure application to only one side of thepiston under the control of the regulator for efiecting change in theopposite direction.

In order to provide for synchronizing the adlusting movements of all ofthe blades, the teeth of each bevel gear 88 are adapted to engage withthe beveled teeth of a ring gear 95 which is rotatably joumalled uponball bearings 96 carried upon an extended sleeve portion 91 of the hubl2. Suitable retaining and clamp devices 98 provide for retaining thebearings and the ring gear in position, the ring gear thus engaging thering sectors on each of the several blades so as to assure of theiroperation and rotation in coordinated and synchronized movements.

The invention therefore provides a highly satisfactory adjustable bladepropeller which is simple in construction and in which the blades areIii adjustable rapidly and accurately over a wide range of positionings,which if desired may extend from a position of negative pitch to aposition where the blade is fully feathered. And with the combined slowand rapid rate of adjustment, provision is made for securing highlyaccurate adjustment of the blade setting in the normal operating rangeso as to provide for maintaining a predetermined speed condition withaccuracy, while simultaneously providing for shifting the blade morerapidly into a feathered position. The mechanism is well balancedkinetically, and provides for retaining a desired condition of bladesetting without the necessity for the continuous application of fluidpressure thereto so that within the operating range the blade positionwill be held even in the event of failure of the fluid pressure system.Likewise the blade actuating mechanism and the supply of pressurecontrol fluid is such that the hollow driveshaft is left completelyclear so that it is adapted for such use as may be desired, for example,the firing of projectiles therethrough.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, fluid pressure actuated means within said hollowroot portion, means mechanically interconnecting said fluid pressuremeans with said blade for effecting controlled positive rotation of theblade in both directions, the weight and mass distribution of the bladeand of said fluid pressure means being correlated such that the forcestending to effect increase in the pitch of the blade are substantiallyin balance with those tending to effect decrease thereof in apredetermined blade position within the normal operating range and meansfor supplying fluid selectively to said fluid pressure actuating meansto cause positive operation thereof in both directions to effect bothpitch increasing and pitch decreasing adjustment of the blade.

2. An hydraulically adjustable propellerof the character described whichcomprises a hub, a blade socket formed in said hub, a blade having ahollow root portion extending into said socket, means for mounting saidblade in said socket for rotation with respect thereto to vary the pitchof the blade, fluid pressure actuating means for eifecting rotation ofthe blade in opposite directions including a cylinder within said hollowroot and directly connected to said blade, a piston movable radiallywithin said cylinder, a skirt movable with said piston, and meansintercon necting said cylinder and said skirt providing for rotatingsaid blade relatively slowly over the normal working range of bladepositions and relatively rapidly into a feathered position.

3. An adjustable propeller of the character described having itsoperating mechanism located entirely clear of the propeller axis whichcomprises a hub. a blade socket formed in said hub, a blade having ahollow root portion extendin into said socket, means for mounting saidblade in said socket for rotation with respect thereto to vary the pitchof the blade, means movable radially of the blade within said hollowroot portion over a predetermined range of movement,

means interconnecting the blade and said movmeans for mounting saidblade in said socket for rotation with respect thereto to vary the pitchof the blade, fluid operated actuating means having a movementsubstantially radially of the propeller shaft for effecting rotation ofthe blade, means interconnecting said blade and said fluid operatedactuating means for effecting slow movement of the blade in one portionof the radial movement of said fluid actuating means, and additionalmeans operable in a predetermined portion of the radial movement of thefluid actuating means for efi'ecting rapid movement of the blade.

5. An adjustable propeller of the character described having itsoperating mechanism located entirely clear of the propeller axis whichcomprises a hub, a blade socket formed in said hub, a blade having ahollow root portion extending into said socket, means for rotatablyretaining said blade in said socket providing for adjustment of thepitch angle thereof, a cylinder fixed in said blade root, a pistonradially movable in said cylinder, a stationary member fixed to the huband extending into said hollow root portion, means connecting saidpiston with said stationary member to cause said piston to occupy apredetermined angular positioning throughout its radial movement, ahelical spline connection for eflecting direct rotational movement ofsaid cylinder in response to radial movement of said piston, and aconduit for the supply of fluid pressure to said piston to effectoperation thereof, the

path of fluid supply to said pitson including said helical splineconnection to provide for forced lubrication thereof.

6. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, fluid pressure actuating means for effectingrotation of the blade including a cylinder positioned within said hollowroot portion, a piston radially movable within said cylinder, a floatingspline member having helical spline teeth engaging upon opposite sidesthereof respectively with said cylinder and with said piston, saidspline teeth having different angles of lead to provide for producingdifferent corresponding rotational movements of said cylinder uponmovement of said piston, and means for controlling the movement of saidfloating spline member to provide for predetermined adjusting movementof said blade.

7. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a

blade socket formed in said hub, a blade having a hollow root portionextending into said socket,

means for mounting said blade in said socket for rotation with respectthereto to vary the pitch of the blade, fluid pressure actuating meansfor effecting rotation of the blade including a cylinder positionedwithin said hollow root portion, a piston radially movable within saidcylinder, a floating spline member having helical spline teeth engagingupon opposite sides thereof respectively with said cylinder and withsaid piston, said spline teeth having different angles of lead toprovide for producing diiferent corresponding rotational movements ofsaid cylinder upon movement of said piston, and means for controllingthe relative movement between said piston and said floating spline, andbetween said cylinder and said floating spline to secure selectiverelative rotation of said cylinder and said blade.

8. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, fluid pressure actuating means for effectingrotation of the blade including a cylinder positioned within llld hollowroot portion, a piston radially movable within said cylinder, a floatingspline member having helical spline teeth engaging upon opposite sidesthereof respectively with said cylinder and with said piston, saidhelical teeth upon the opposite sides of said floating spline memberhaving different angles of lead, and cooperating parts formed on saidcylinder and said piston providing for forcing relative movement betweensaid teeth having the greater angle of lead following initial movementbetween teeth having the lesser angle of lead.

9. An adjustable propeller of the character described which comprises ahub, a blade socket formed in said hub, a blade having a hollow rootportion extending into said socket, means for mounting said blade in'said socket for rotation with respect thereto to, vary the pitch of theblade, actuating means for effecting rotation of the blade including acylinder positioned within said hollow root portion, a piston movable insaid cylinder axially thereof, a stationary cylindrical member extendinginto said hollow root and flxed to said hub, a skirt carried by saidpiston having a spline connection upon the inner and outer facesthereof, said cylindrical member having spline teeth for engaging saidskirt to provide for maintaining the piston in a predetermined angularpositioning throughout its axial movement, and a floating spline havingengagement with the outer spline teeth on said skirt and with innerspline teeth on said cylinder, and providing for interconnecting saidparts to cause adjustment of the pitch of the blade in response to axialmovement of said piston, the direction of lead of all of said splineteeth being the same to cumulate the rotational effect thereof uponoutward movement of said piston.

10. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, fluid pressure actuating means loincluding acylinder positioned within said hollow root and connected with saidblade, a piston radially movable within said cylinder and having a skirtand a tubular piston rod attached thereto, a stationary member withinsaid hollow root and fixed to said hub, means for interconnecting saidpiston and said stationary member providing for relative movementtherebetween a fluid sealed connection in said stationary member forslidably receiving said piston rod therethrough, means for introducing afluid actuating medium under pressure interiorly of said stationarymember to be supplied through said hollow piston rod to the outer faceof said piston in order to cause movement thereof radially inward,additional means for supplying fluid actuating medium under pressureoutwardly of said stationary memher to be effective upon the inner sideof said piston to cause movement thereof radially outwardly, said skirtbeing apertured to provide for passage of said fluid to the inner sideof said piston and a helical spline connection between said piston andsaid cylinder for efiecting rotation of the latter in response to saidmovement of the piston, said spline connection being within the path 'ofsaid pressure fluid and adapted to be lubricated thereby.

11. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havinga hollow root portion extending into said socket,

means for mounting said blade in said socket for rotation with respectthereto to vary the pitch of the blade, a cylinder within said hollowroot portion, a piston member operating in said cylinder and having apredetermined weight directly subject to centrifugal force upon rotationof said hub. said piston member being movable outward- 1y with respectto said hub, means for interconnecting said piston member and said bladeto provide for pitch increasing adjustment of said blade upon outwardmovement of said piston member and for pitch decreasing adjustment ofsaid blade upon inward movement of said piston member, the weight ofsaid piston member and the forces tending to eifect pitch increasingadjustment being coordinated with the centrifugal blade torque and theother forces tending to effect pitch decreasing adjustment so that saidforces tending to effect pitch increasing adjustment are notpredominately greater than those tending to effect pitch decreasingadjustment in the normal operating position of the blade, and

controllable means for introducing fluid pressure to said piston toeflect positive controlled movements of said piston member withcorresponding pitch increasin and pitch decreasing adjusting movement ofsaid blade.

12. An hydraulically adjustable propeller of the character describedwhich comprises a hub, ,a blade socket formed in said hub, a bladehaving a hollow root portion extending into said socket, means formounting said blade in said socketfor rotation with respect thereto tovary the pitch of the blade, a cylinder within said hollow root portion,a piston operating in said cylinder, a weighted member associatedtherewith and subject to centrifugal force upon rotation of said hub,said weighted member being movable outwardly with respect to said hub,means for interconnecting said weighted member and said blade to providefor pitch increasing adjustment of said blade upon outward movement ofsaid weighted member and for pitch decreasing adjustment of said bladeupon inward movementof said weighted member, the weight of saidweightedmember and the forces tending to effect pitch increasingadjustment being coordinated with the centrifugal blade torque and theother forces tending to effect pitch decreasing adjustment so that saidpitch increasing forces are less than those required to effect pitchincreasing adjustment in the normal operating position of the blade andin the absence of fluid pressure application, and controllable means forselectively introducing fluid pressure to each side of said piston toeffect positive controlled movement of said weighted member in eachdirection with corresponding adjusting movement of said blade.

13. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in the hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, 8. cylinder within said hollow root portion, apiston member operating in said cylinder subject to centrifugal forceupon rotation of said hub and being movable outwardly with respect tosaid hub within said hollow root portion, means for interconnecting saidpiston member and said blade to provide for pitch increasing adjustmentof said blade upon outward movement of said piston member and for pitchdecreasing adjustment of said blade upon inward movement thereof, theweight of said piston member and the forces tending to eflect pitchincreasing adjustment being predetermined with respect to thecentrifugal blade torque to be opposed to and not eflectively greaterthan such centrifugal blade torque and the other forces tending toeffect pitch decreasing adjustment, and controllable means forintroducing fluid pressure to the inner side of said piston to force thesame outwardly under positive pressure application for increasing thepitch of said blade.

14. An hydraulically ad'ustable propeller of the character describedwhich comprises a hub, a blade socket-formed in said hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, fluid pressure actuated means including a weightedmember mounted within said hollow root portion and movable with respectto said hub for eflecting rotation of the blade in both directions andsubject to centrifugal force, means for interconnecting said blade andsaid weighted member to provide for the eifect of centrifugal force onthe latter acting in a direction to tend to increase the pitch of theblade, the weight of said member being such that the effect ofcentrifugal force acting thereon substantially reduces but does notexceed the effect of centrifugal blade torque in a position fallingwithin the normal operative range'of blade positions, and means forsupplying fluid selectively to said fluid pressure actuated means tocause positive operation thereof in both directions to effect pitchincreasing and itch decreasing adjustment of the blade.

15. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, fluid pressure actuated means including a weightedmember located in said hollow root portion and subject to centrifugalforce for effecting rotation of the blade, means interconnecting saidweighted member and said blade to effect rotation of the latter indirect response to movement of said fluid pressure actuated means, saidinterconnecting means requiring application of an actuating force inexcess of a predetermined value to cause movement of said fluid pressureactuated means, the weight of said member and the centrifugal bladetorque acting upon the blade being such that the resultant of the forcestending respectively to cause increase and decrease of the pitch of theblade in blade positions within the normal operative range is less thansaid predetermined value to provide for retaining the blades in apredetermined adjusted position within such normal operating range,

and means for selectively applying fluid pressure to said fluid pressureactuated means to produce a force in excess of said predetermined valuethe blade in a predetermined adjusted position within the normaloperating range and opposing the tendency of the forces acting thereonto rotate said blade, and means for supplying fluid with resulting pitchincreasing or pitch decreasing adjustment of the blade.

16. An hydraulically adjustable propeller of' the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havinga hollow root portion extending into said socket, means for mountingsaid blade in said socket for rotation with respect thereto to vary thepitch of the blade, fluid pressure actuated means including apistonlocated in said hollow root portion and directly subject tocentrifugal force, means interconnecting said fluid pressure actuatedmeans and said blade to effect rotation of the latter, the centrifugalforce effective upon said piston acting in opposition to the effect ofcentrifugal blade torque, said interconnecting means having substantialfrictional force such as to provide for retaining the blades inpredetermined adjusted position within the normal operating rangeagainst the tendency of said opposing forces to cause change in thepitch thereof, and means for supplying fluid to said fluid pressureactuated means under positive pressure suf-' ilcient to overcome saidfrictional force and to effect adjustment of the pitch of the blade inboth directions.

17. An hydraulically adjustable propeller of the character describedwhich comprises a hub, a blade socket formed in said hub, a blade havina hollow root portion extending into said socket.

means for mounting said blade in said socket for rotation with respectthereto to vary the pitch pressure selectively to said fluidpressureactuated means under positive pressure sufficient to overcomesaid retarding forces and to adjust the position of the blade in bothdirections to effect controlled pitch increasing and pitch decreasingadjustment of the blade;

18. An hydraulically adjustable propeller of the character describedwhich comprises a. hub, a blade socket formed in said hub, a bladehaving a hollow root portion extending into said socket, means formounting said blade in said socket for rotation with respect thereto tovary the pitch of the blade, fluid pressure actuated means for effectingrotation of the blade including a cylinder element positioned withinsaid hollow root portion, a piston element axially movable in saidcylinder, an abutment flxed with respect to said hub and extending intosaid hollow root portion, said abutment, said piston, said cylinder andsaid blade socket all being located coaxially, annular spline meanshaving teeth arranged around the periphery thereof and directlyconnecting said piston and said cylinder to maintain the rotating forcesdistributed around the periphery thereof, one of said piston andcylinder elements being operatively connected to said blade, and annularspline means having teeth arranged around the periphery thereof forconnecting the other of said piston and cylinder elements tov saidabutment, at least one of said spline means being spiral to provide fordeveloping a rotational force upon said blade socket on relativemovement between said cylinder and said piston while maintaining all therotating forces of the blade, said blade being subject to centrifsomummy distributed relationugal blade torque tending to reduce the pitchthereof in operation, fluid pressure actuated WERNER J. BLANCHARD.

CHARLES S. J. MACNEIL.

